As gas sensor devices to measure the concentration of a given gas component in a measurement gas, there are ones equipped with a pump cell working to control the concentration of oxygen contained in measurement gas taken thereinto. The control of the concentration of oxygen by the pump cell avoids an error in determining the concentration of the given gas component using a sensor cell of the gas sensor device which arises from oxygen contained in the measurement gas.
Japanese Patent First Publication No. 8-271476 discloses a gas sensor device which is equipped with a first inner void from which a pump cell discharges oxygen in a measurement gas and a second inner void in which a sensor cell measures the concentration of a given gas component of the measurement gas. The gas sensor device also includes a first diffusion rate controlling path in which the measurement gas introduced into the first inner void is controlled in diffusion rate thereof and a second diffusion rate controlling path provided between the first inner void and the second inner void.